1. Field of the Invention
The present invention relates to a device for applying ultrasound energy to a patient for therapy in either a continuous or a pulsed mode.
2. Description of the Prior Art
Ultrasound applicator devices are known for transmitting either continuous or pulsed ultrasound energy, such as to the body of a patient for treatment of various maladies. In our earlier U.S Pat. No. 4,368,410, assigned to the same assignee as is the present invention, a servo feedback loop measures actual power delivered to a transducer to adjust the output as loading conditions at the transducer change. The changing load conditions are a result of the different absorption of ultrasound energy by different types of tissue, as well as of changing degrees of coupling between the transducer and the patient's body. The servo feedback is provided by supplying signals representative of voltage and current at the transducer to an analog multiplier to maintain the output power to the transducer at the selected level. The device enables the operator to select not only a pulse period, but also a pulse duration through front panel touch pad switches.
It is also known to provide ultrasound devices with interchangeable transducer heads although recalibration is required, devices that operate at more than one ultrasound frequency, and ultrasound devices that interrupt the output when the transmitted ultrasound energy falls below a predetermined level.